"This paper does suggest that child abuse content is the most popular type of content on the Tor Dark Net. While law enforcement may crawl such sites, the number of requests that would be seen would be only a tiny fraction, and hence not skew the outline ratios. Similarly, denial of service attacks were not observed and so are also unlikely to account for the high requests. The usage of Tor2Web may underrepresent some categories, but it is not currently clear whether, or why, such groups would exclusively use this tool." (Page 9)